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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-06-21 15:43:21 +02:00
Christian Brauner
6ece1a31c5
Jens Axboe <axboe@kernel.dk> says: One of the nastier things about epoll is how it allows nesting contexts inside each other, leading to the necessity of loop detection and the issues that have come with that. I don't believe there's any reason to support nesting on the io_uring side, in fact IORING_OP_EPOLL_CTL is a historical mistake, imho. But let's at least try and contain the damage and disallow nested contexts from our side. Christian Brauner <brauner@kernel.org> says: Bring in the eventpoll specific io_uring changes together with the eventpoll cleanup I did this cycle. The io_uring changes can go on top of both through the block tree. * patches from https://patch.msgid.link/20260514140817.623026-1-axboe@kernel.dk: eventpoll: rename struct epoll_filefd to epoll_key eventpoll: add file based control interface eventpoll: export is_file_epoll() eventpoll: pass struct epoll_filefd through ep_find() and ep_insert() Link: https://patch.msgid.link/20260514140817.623026-1-axboe@kernel.dk Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
109 lines
3.0 KiB
C
109 lines
3.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* include/linux/eventpoll.h ( Efficient event polling implementation )
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* Copyright (C) 2001,...,2006 Davide Libenzi
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*
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* Davide Libenzi <davidel@xmailserver.org>
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*/
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#ifndef _LINUX_EVENTPOLL_H
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#define _LINUX_EVENTPOLL_H
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#include <uapi/linux/eventpoll.h>
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#include <uapi/linux/kcmp.h>
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/* Forward declarations to avoid compiler errors */
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struct file;
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#ifdef CONFIG_EPOLL
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#ifdef CONFIG_KCMP
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struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff);
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#endif
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/* Used to release the epoll bits inside the "struct file" */
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void eventpoll_release_file(struct file *file);
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/* Copy ready events to userspace */
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int epoll_sendevents(struct file *file, struct epoll_event __user *events,
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int maxevents);
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/*
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* This is called from inside fs/file_table.c:__fput() to unlink files
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* from the eventpoll interface. We need to have this facility to cleanup
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* correctly files that are closed without being removed from the eventpoll
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* interface.
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*/
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static inline void eventpoll_release(struct file *file)
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{
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/*
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* Fast check to skip the slow path in the common case where the
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* file was never attached to an epoll. Safe without file->f_lock
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* because every f_ep writer excludes a concurrent __fput() on
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* @file:
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* - ep_insert() requires the file alive (refcount > 0);
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* - ep_remove() holds @file pinned via epi_fget() across the
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* write;
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* - eventpoll_release_file() runs from __fput() itself.
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* We are in __fput() here, so none of those can race us: a NULL
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* observation truly means no epoll path has work left on @file.
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*/
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if (likely(!READ_ONCE(file->f_ep)))
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return;
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/*
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* The file is being closed while it is still linked to an epoll
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* descriptor. We need to handle this by correctly unlinking it
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* from its containers.
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*/
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eventpoll_release_file(file);
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}
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struct epoll_key {
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struct file *file;
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int fd;
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} __packed;
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int do_epoll_ctl_file(struct file *f, int op, struct epoll_key *tf,
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struct epoll_event *epds, bool nonblock);
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int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
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bool nonblock);
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bool is_file_epoll(struct file *f);
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/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
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static inline int ep_op_has_event(int op)
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{
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return op != EPOLL_CTL_DEL;
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}
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#else
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static inline void eventpoll_release(struct file *file) {}
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#endif
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#if defined(CONFIG_ARM) && defined(CONFIG_OABI_COMPAT)
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/* ARM OABI has an incompatible struct layout and needs a special handler */
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extern struct epoll_event __user *
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epoll_put_uevent(__poll_t revents, __u64 data,
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struct epoll_event __user *uevent);
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#else
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static inline struct epoll_event __user *
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epoll_put_uevent(__poll_t revents, __u64 data,
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struct epoll_event __user *uevent)
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{
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scoped_user_write_access_size(uevent, sizeof(*uevent), efault) {
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unsafe_put_user(revents, &uevent->events, efault);
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unsafe_put_user(data, &uevent->data, efault);
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}
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return uevent+1;
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efault:
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return NULL;
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}
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#endif
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#endif /* #ifndef _LINUX_EVENTPOLL_H */
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